LAMAR, Colo. -- Ranchers, pilots and snowmobilers on Wednesday searched for thousands of cattle trapped by heavy snow and high drifts in southeastern Colorado, while hundreds of cows were reported dead in Kansas.

Eight National Guard helicopters and a C-130 cargo plane were dispatched in the campaign to save the livestock herds snowed in by back-to-back holiday blizzards. Volunteer snowmobile search-and-rescue groups from elsewhere in the state joined the effort on the ground.

"We think there are probably 30,000 head out there that are at risk that we're having to make sure we feed," said Maj. Gen. Mason Whitney of the Colorado Guard.

In southwestern Kansas, an undetermined number of cows has died. One feedlot owner in Haskell County, Kan., said he lost 450 cattle and 20 dairy cows.

"I don't know what we are going to do, how we are going to dispose of them," County Commissioner Gene Ochs said of the carcasses.

Emergency crews worked through the long weekend to rescue stranded motorists, evacuate people with health problems and deliver food, water and medicine to the region's snowbound residents.

Utilities in sections of Nebraska, Kansas and Oklahoma worked around the clock to restore electricity to tens of thousands of homes and businesses, but officials said it could be weeks for some of the most isolated, rural customers.

At least 21,000 customers in western Kansas were without power, as were an estimated 15,000 customers in Nebraska and about 2,500 in Oklahoma. Nebraska state officials estimated tens of millions of dollars in damage to power lines and other equipment.

The storm was also blamed for at least 13 deaths.

The storm covered more than half of the nation's major cattle-feeding areas, said Kevin Good, a senior analyst with Cattle Fax, a cattle market information service.

On Wednesday, ranchers rode with pilots to spot cattle and creeks for water in Colorado. Crews in smaller helicopters landed near frozen streams and used sledgehammers to chop ice from the water.

Soldiers delivered about 500 bales of hay Tuesday to cattle unable to get through the snow to grass and water, Whitney said.